Aircraft tracking colored smoke marker



1966 w. w. REAVES ETAL 3,229,633

AIRCRAFT TRACKING COLORED SMOKE MARKER Original Filed July 14. 1961 INVENTORS Kenneth G. Gar/an Woodrow M Reaves ATTORNEY United States Patent Office 3,229,633 Patent ed Jan. 18, 1966 3,229,633 AIRCRAFT TRACKKNG CQLURED SMOKE MARKER Woodrow W. Reaves, Baltimore, and Kenneth G. Carlon,

Aberdeen, Md, assignors to the United States of America as represented by the Secretary of the Army Original application July 14, 1961, der. No. 124,733, now Patent No. 3,121,231, dated Feb. 11, 1964. Divided and this application Dec. 3, 1963, Ser. No. 331,985

6 Claims. (Cl. 1tl237.4) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This is a division of Patent No. 3,121,231, filed July 14, 1961 entitled Aircraft Tracking Colored Smoke Producing Composition.

This invention is related to the art of making high speed and high altitude aircraft or missiles visible to the naked eye. This is accomplished by burning a mixture of an organic dye with a fuel and an oxidizer from a special container within or attached to the aircraft or missile.

It is well known in the prior art how to make colored smoke for signal rockets, smoke pots and the like. This is illustrated by the following Patents: 2,543,006; 1,319,- 329; 2,419,851 and 1,339,142, and the article in Chemical and Engineering News, vol. 22, #22, November 25, 1944, pages 1990-91, 2056.

In the above prior art, it was common to have an oxidizer and a fuel to vaporize the organic dye. There could also :be a cooling agent to lower the temperature of combustion to prevent or decrease the decomposition of the dye. These compositions were designed solely for use at or near sea level.

The present invention is a composition and apparatus for supporting it in use which is designed to be used at an altitude of 30,00040,000 feet or higher. The existing compositions simply do not function at the low temperatures and low oxygen prevalent at the high altitudes for which the invention is designed.

Thus, the invention is useful to establish visual contact between jet aircraft prior to a refueling operation. It is further useful as an aerial smoke marker for tracking air movements in the upper atmosphere.

Still further use of the invention lies in its ability to aid in the optical tracking of missiles (air to air and ground to air) since the use of a brilliant color in direct contrast to the blue sky or cloudy sky leaves no doubt as to where the missiles have been or where they are going.

As will be shown later, the compositions set forth in the above prior art were found to be ineffective for use in the high altitudes. Consequently, We had to develop a formulation that would function properly high in the sky. We also had to develop a carrier to hold the composition while it was formed.

It was found during the development work on this invention that the mix or formulation does not always burn uniformly. With certain percentage ranges of the fuel, dye and oxidizer, We found that a surging occurred. In other words, sometimes the outlet of the canister Was actually blocked by the molten contents therein. This caused a pressure build up in the canister until the mix was again blown through the outlet. This fact and the ever present chance of human error in compounding the formulation led us to devise the present carrier for aircraft shown in the drawings which has a unique safety feature. If the surging persists too long and the pressure becomes too great, the wooden or plastic nose cone of the canister is designed to blow out, thus relieving the pressure. Likewise, the same result obtains if the wrong mix is placed in the canisters. In this case, instead of the canister exploding and damaging the aircraft, the nose cone is ejected with little or no damage to the canister or the aircraft.

Referring now to the drawings, FIG. 1 is an isometric view of one embodiment of the invention.

FIG. 2 is a plan View partly in section of the same embodiment.

In the drawing, item 3 represents the electric squib or fuze which is used to set off the mix or composition 17. Immediately below the squib is the exit hole 5 from which the colored smoke issued. The hole 5 is covered by a sealing tape 6 to exclude moisture. The canisters 11 are attached to four cross bars 10 of which only the top two are shown. These bars 10 are in turn attached to a channel iron 7. On this channel iron are mounted two lugs 8 for attachment of the device to the wings or fuselage of an aircraft. Obviously, the device can include a plurality of canisters. The number to be used is a matter of choice depending upon the size and weight of each canister.

Each of the canisters has a somewhat streamlined nose 9 made of wood or plastic. The one shown is conical or pointed but any other streamlined shape such as bulletnosed may be used. The nose 9 is held in place by wood screws 12. This is an important facet of the present invention since if the cartridge should explode or exceed a certain amount of pressure, the screws 12 will pull out or shear off and allow the nose cone to blow out, thus relieving the pressure and preventing damage to the air craft wing or fuselage.

The mix or composition 17 is held in a cartridge which is defined by the cylinder 15 and ends 25 and 29. Inside this cartridge is a first retainer ring 20 with an asbestos disc 19. This ring 20 is provided with set screws 18 so that it can be adjustably placed about an inch from the end of the canister to provide a greater area of combustion during the critical ignition period and to provide for expansion of the composition during its combustion.

This device is essentially a reusable carrier for the cartridges. In order to prevent the heat of combustion from warping or otherwise deteriorating the canisters 11,

' we have provided asbestos insulating means such as the washers 23 and 27 and canister liner 13.

On the end of canister 11 we provide a second retaining ring 21 with set screws 22 which keeps the cartridge in place. After the cartridge has been fired from electric controls in the airplane, the cartridge can be replaced by a new one by merely unscrewing the set screws 22 back into the canister 11 and pulling out the retaining ring 21 and the cartridge.

The firing mix or composition was developed by us as a result of a series of test firings as set forth in the following tables:

TABLE I Ground firing test of aircraft tracking marker Formulation Parts by Burning Remarks weight time Ignition, color and volume of smoke were satisfactory. tieveral variations in e ignig 2 tion were tried. Sev- 5 2-3 min eral units were given 2. 5 vibration test, a rough handling test, and a few were fired at I All were considered satisfactory.

3 TABLE II Flight tests of the formulation of Table I Air Speed, knots Units burned for approximately 3 min. Good volume of smoke.

Units burned for 3 min. Good volume of smoke. During a dive there was a slight dissipation of smoke.

20 see. after ignition the units emitted a very faint trace of smoke not visible to the naked eye but discernible through a 10 power telescope. After 45 see. the burning rate increased and a faint trace of smoke was visible to the naked eye for approximately 5 min.

Units were ignited under the same conditions as test #3 with the same results except that the burning rate did not increase and at no time was the smoke visible to the naked eye.

TABLE III Comparison of the burning times of units at sea level and 30,000 feet Composition Altitude Burning time Remarks The units Fore grought to 65 an stati- 42. gfi gg f Seal 1 1 1 cally fired. The i hl.

Sulfur We m n iid 355 1 11255565?" NaHCO 25.5-- The smoke was con sidered satisfactory.

Same 30,000 5 min. 30 sec Speed 140 knots. Smoke to 6 min. trail was very faint.

TABLE IV Tests conducted to speed up burning time at sea level Test Formula- Parts by Burning time Remarks tion weight Too much surging, i.e. E??? ii 5 i t ti i i i' 3-... na ey e an Sulfur 12. 1 25 unblocked by the slag NaHOO3 10.0 that forms on these formulations. 53. 5

g 1 min. sec. Same as above. 3. 5 57. 00 KOlO3 31. 00 52 sec Same as above. Sulfur 12.00

4".-- Red dye 50.00 Ignition was good.

KClO 26.00 45 sec Color and volume of Thiourea 24. 00 smoke were good.

5 Red dye 56 KCl0a 24 55 sec Thiourea 24 6".-- Red dye 70 gg gi- Impossible to ignite.

Urea 7 3 Thiourea 18 45 Sec Urea 7 8 Red dye 52 gfiggg- 1 min. 12 sec Ignition lag at -e5 F. Urea 6 9 Red dye 50 ggigi- Z3 1 min. 25 sec Same as above. NaHCO 10 10 dye 5 Iggition 1Watts slow.d d

03. pecia s arters i not Thiourea 22. 5 1 improve ignition at NaHC0 12. 5 5 F.

11 Red dye 56 Smoke volume and burn- KOlO3.. 20 1 min. 10 sec... ing time were satis- Thiourea 20 Ufa rtory. h

12 Red dye 60.00 m S w glyen r-oug K0103".-- 20.00 1 min. 10 sec-.. hagdhngi brawn Thiourea 20' 00 an 40 it. drop tests and were found satisfactory.

a TABLE IVC0ntinued Test Formula Parts by Burning time Remarks tion weight g N 0 time {Ignition very slow be- Thiourea 1s cause of 14".. Red dye 42 g gggz 1 min. 39 sec. Ignition lag. NaIIC 0a-.. 14 15 Red dye 57 Ignition, smoke color KOlOa. 2 min and volume were satis- Thiourea 18 factory. 16..-. Red dye 57 KClO3.. 25 2 min Same as test #12. Thiourea 18 TABLE V Flight tests of compositions Test Formula- Parts by Burning time Remarks tion weight 1a Red dye 60 Altitude 30,000 ft. speed K0103... 20 1 min 150 knots, ignition and Thiourea 2O smoke satisfactory. 1b Same as above 1 min. sec--- Same. 1c Same as above 2 min Same.

Air temperature -40 2a Red dye 57 F. altitude 30,000,

KClO3 25 3 minspeed 247 knots. Thiourea 18 GOlid, visible smoke trai 2b Same as above 2 min. sec. Same. 2c Same as above 2 min. 15 sec Same. 3a. Same as above 3 min. 10 sec... Altitude 30,000 temp.

45 F. speed 570 knots, smoke trail excellent. 3b Same as above N 0 time taken Altitude 4043,000 temp.

60 F., speed 470 knots, smoke trail excellent.

Note 1. In all the above tables the composition was pressed into the canisters under 20 tons pressure.

N ate 2. The red dye used was l-methylaminoanthraquinone.

Note 3. The formulations are given in parts by weight not in percentage by weight for convenience in compounding.

We have illustrated our invention with only one heat stable dye. It is obvious that other brightly colored dyes could be used in place of the red dye used above. Thus, the yellow, orange or violet dyes set forth in the aforementioned Chemical and Engineering News article can be substituted in the above formulations. The only requirements for the dye to be used is that they contrast sharply with the natural blue sky and that they are relatively heat stable.

In general the composition we have developed for high altitude tracking has in it a range of fuel from 15-25 parts by weight with the oxidizer being present in approximatcly equal amounts. The heat stable dye is present in the mixture in an amount such that the approximate total weight of the dye, oxidizer and fuel is about units. We have found that a mixture of 57 parts by weight 1- methylaminoanthraquinone, 25 parts by weight potassium chlorate and 18 parts by weight of thiourea gives the best results for this work. This has met the requirements of the U.S. Navy for such a composition.

We have found further that another fuel, tetramcthyl thiuram disulfide may be used for the thiourea used above with approximately the same results.

We claim:

1. A device for holding a colored smoke composition on an aircraft during a high altitude flight consisting of a holder mounted on said aircraft, said holder having a plurality of canisters mounted thereon, said canisters having a pointed end on one end thereof, in which the pointed end of said canisters is automatically ejected only in the event the pressure generated in said canister exceeds a predetermined limit, each of said canisters having a removable retainer at the end thereof remote from said pointed end, a plurality of replaceable cartridges mounted within said canisters, said cartridges consisting substantially of a mixture of a heat-stable organic dycstuif, and

an oxidizing agent impacted therein, means on said retainer for igniting said cartridges where-by the retainer can be removed and a new cartridge inserted into each of the canisters after firing.

2. A device as set forth in claim 1 in which insulating means is placed on the interior of each canister.

3. A device for holding a colored smoke composition on an aircraft during a high altitude flight consisting of a holder adapted to be mounted on said aircraft, said holder consisting of a pair of lower cross bars and a central channel iron having a pair of top cross bars, means on said channel iron for detachably mounting said device to said aircraft, a pair of canisters attached between said top and lower cross bars, said canisters having a substantially streamlined nosecone at one end thereof and a manually removable end remote from said nosecone, said streamlined end of said canisters is automatically ejected only in the event the pressure generated in said canister exceeds a predetermined limit, a pair of combustible replaceable cartridges mounted within the canisters through the opening at said removable end, fuze means mounted on the terminal end of said cartridge at said removable end of said canister whereby after firing by means of said fuze means the spent cartridges may be replaced.

4. A device as set forth in claim 3 in which the streamlined nosecone is held in place by wood screws.

5. A device as set forth in claim 3 in which the streamlined nosecone is made of plastic.

6. A device as set forth in claim 3 in which the streamlined nosecone is made of wood.

References Cited by the Examiner UNITED STATES PATENTS 1,209,560 12/1916 Cosner 248-300 1,219,596 3/1917 Simmons 248-300 2,199,990 5/1940 Godfrey et al.

2,565,352 8/1951 Champney et al 102-90 2,751,582 6/1956 Kuykendall 102-374 X 3,055,269 9/1962 Clark et a1 102-37.4 3,068,756 12/1962 Schermuly 89-1.5 3,121,231 2/1964 Reaves et al. 149-64 BENJAMIN A. BORCHELT, Primary Examiner. SAMUEL FEINBERG, Examiner. R. F. STAHL, Assistant Examiner. 

1. A DEVICE FOR HOLDING A COLORED SMOKE COMPOSITION ON AN AIRCRAFT DURING A HIGH ALTITUDE FLIGHT CONSISTING OF A HOLDER MOUNTED ON SAID AIRCRAFT, SAID HOLDER HAVING A PLURALITY OF CANISTERS MOUNTED THEREON, SAID CANISTERS HAVING A POINTED END ON ONE END THEREOF, IN WHICH THE POINTED END OF SAID CANISTERS IS AUTOMATICALLY EJECTED ONLY IN THE EVENT THE PRESSURE GENERATED IN SAID CANISTER EXCEEDS A PREDETERMINED LIMIT, EACH OF SAID CANISTERS HAVING A REMOVABLE RETAINER AT THE END THEREOF REMOTE FROM SAID POINTED END, A PLURALITY OF REPLACEABLE CARTRIDGES MOUNTED WITHIN SAID CANISTERS, SAID CARTRIDES CONSISTING SUBSTAN- 